Dr. Lemas will be investigating the biological mechanisms that help explain why infants born to obese and overweight mothers have increased adiposity during the first year of life. Animal models suggest the gut microbiome may be an important factor mediating the transfer of obesity risk from mother to infant during pregnancy, yet information defining how such maternal features as obesity impact microbial colonization and infant adiposity remains unclear. Dr. Lemas’s proposal is devoted to understanding how maternal obesity acts to reprogram the microbiome of the mother-infant pairs during the first 4 months of life and to establish how this critical window of development impacts maternal characteristics, the infant microbiome, and infant adiposity. The overarching hypothesis motivating his work is that the maternal microbiome in mothers with distinct phenotypes (from normal weight to obesity) will directly affect the development of the infant’s microbiome and adiposity during the first 4 months of life.

Under this NRSA award, Dr. Lemas will analyze a subset of data from an ongoing longitudinal cohort study that has comprehensively characterized 40 mother-infant pairs over the first 4-months of life. The maternal phenotypes in this study are selected according to mother-infant pairs in each of the following study groups: normal weight (NW) and obese (Ob). Maternal stool and human milk samples will be used to characterize maternal microbial exposure, and infant stool samples will be used to characterize the infant microbiome. The specific questions to be addressed in this proposal are three-fold: to determine 1) how obesity impacts the maternal microbiome during late pregnancy and through the first 4 months postpartum; 2) how infant exposure to the maternal microbiome among women with obesity affects the infant microbiome during the first 4 months of life; and 3) whether the maternal-infant microbiome is a major determinants of infant adiposity through the first 4 months of life.

Ultimately, the results of Dr. Lemas’s project will provide a deeper understanding of how maternal obesity acts to reprogram the microbiome in mother-infant pairs and help to dissect the mechanisms linking maternal characteristics to infant adiposity through changes to the human microbiome.